title: Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: a re-analysis of Attewell, Glase and McFadden, 2001.
abstract: This paper shows that the meta-analysis of bicycle helmet efficacy reported by Attewell, Glase, and McFadden (Accident Analysis and Prevention 2001, 345-352) was influenced by publication bias and time-trend bias that was not controlled for. As a result, the analysis reported inflated estimates of the effects of bicycle helmets. This paper presents a re-analysis of the study. The re-analysis included: (1) detecting and adjusting for publication bias by means of the trim-and-fill method; (2) ensuring the inclusion of all published studies by means of continuity corrections of estimates of effect rely on zero counts; (3) detecting and trying to account for a time-trend bias in estimates of the effects of bicycle helmets; (4) updating the study by including recently published studies evaluating the effects of bicycle helmets. The re-analysis shows smaller safety benefits associated with the use of bicycle helmets than the original study.
authors.affiliation: Institute of Transport Economics, Gaustadalléen 21, NO-0349 Oslo, Norway. re@toi.no
authors.forename: Rune
authors.initials: R
authors.lastname: Elvik
mesh_terms: D000063:Accidents, Traffic / Q000517:prevention & control* / Q000706:statistics & numerical data; D001642:Bicycling / Q000293:injuries*; D006259:Craniocerebral Trauma / Q000453:epidemiology / Q000517:prevention & control*; D003430:Cross-Sectional Studies; D006260:Head Protective Devices / Q000592:standards*; D006801:Humans; D015201:Meta-Analysis as Topic; D016017:Odds Ratio; D017594:Publication Bias; D014947:Wounds and Injuries / Q000453:epidemiology / Q000517:prevention & control*